Arrester devices of this type serve as a security against falling for closing apparatus which are equipped with a worm gear rotationally fixedly connected to an output shaft serving as a winding shaft and with a self-locking worm which is in communication with an input shaft.
Arrester devices of this type are used in doors whose leaf weight is not compensated by springs to ensure the safe operation of said doors. A falling of the door leaf is prevented here in the event of a break of the support element at the drive. Arrester devices of this type can be attached directly to the door shaft or be integrated in the drive.
Integrated arrester devices have already become known which intercept the load via a second worm wheel, which runs along without load, in the event of a break of the support element. Arresting mechanisms are further known in which an auxiliary worm gear runs along (almost) free of load and rotates relative to the working worm gear in the event of a break of the support element. Spring-loaded bolts can thereby be released, on the one hand, to latch into corresponding pockets which are suitable to intercept the load in a shape-matched manner. In accordance with another alternative, rotatably supported clamping pieces can be rotated such that they contact the housing wall radially and bring the load to a stop by friction.
An automatically operating locking device is known from DE 22 22 503 C, for example, to prevent an unwanted rolling down of a roller door, roller grills, roller shutters or the like of the initially recited type in which the arrester device consists of two worm gears arranged on the winding shaft each being driven by a separate worm. In this connection, a worm drive is constantly under load as a working drive, while the other worm drive runs along without load as an auxiliary worm drive. The self-locking auxiliary worm, which is supported in a limited axially displaceable manner, is in communication with its auxiliary worm gear free of any self-load. On a failure of the working worm drive, load is transferred to the auxiliary worm drive, with simultaneously the forwarding of the drive torque to the auxiliary worm being interrupted at a designated desired breaking point. The load then becomes stationary due to the self-locking of the auxiliary worm drive, with the auxiliary worm coming into contact with an abutment bolt fixed to the housing. In this known arrester device, the drive worm and the auxiliary worm are fastened to parallel shafts separate from one another whose kinematic connection consists of a spur gear. This known arrester device is very complex in construction due to the second worm shaft of its drive and the necessary bearings.
In accordance with DE 34 33 561 C, this complex structure is simplified in that only one worm gear is provided which meshes with the self-locking worm, on the one hand, and with the auxiliary worm, on the other hand. Both worms are made as globoid half-worms here. The self-locking worm and the auxiliary worm are arranged successively on a common working shaft. The self-locking worm forms a rotationally fixed unit with the drive shaft, whereas the auxiliary worm constantly runs along free of load via a driver and is supported axially displaceably between abutments fixed to the housing for the compensation of the wear at the self-locking worm. In the event of a breakage of the self-locking worm, the self-locking auxiliary worm, which serves as an arresting worm here, supports the load against its abutments.
All the aforesaid variants with an integrated arrester device have a high number of single parts which result in a high assembly effort and thus comparatively high assembly costs.
It is the object of the present disclosure to provide an arrester device of the type first named which permits an operating security which is as good as possible with a construction which is as simple as possible.
In accordance with the present disclosure, the object is solved by an arrester device in accordance with various combinations of the features disclosed herein. Accordingly, the arrester device serving for a closing apparatus, for example a door, has a worm gear rotationally fixedly connected to an output shaft serving as a winding shaft and a self-locking worm which is in communication with an input shaft. An auxiliary worm gear is additionally placed on an eccentric region of the output shaft with clearance, with the auxiliary worm gear likewise having an eccentricity of the same amount and being mounted such that the eccentricities cancel out with respect to the axis of the output shaft, with the auxiliary worm gear being able to follow the movement of the worm gear without load via a toothed region. The auxiliary worm gear serving as security is thereby not subject to any wear during the usual operation. If there is now a break of the support element with the worm gear rotationally fixedly connected to the output shaft due to wear or overload, the auxiliary worm gear rotates with respect to the eccentric portion of the output shaft. The outer diameter of the auxiliary worm gear thereby disengages from a concentric position. In this connection, the eccentricity of the output shaft and of the auxiliary worm gear is designed such that a self-locking occurs.
In accordance with one embodiment of the present disclosure, the auxiliary worm gear moves out of its concentric position toward a cylindrical region of the transmission housing on movement. The eccentricity is designed here such that the self-locking occurs between the auxiliary worm gear and the transmission housing.
Since the total arrester device includes only one part, namely the auxiliary worm gear placed on, it is very simple and cost-effective to assemble. The arrester device works independently of the speed, direction of rotation and installed position of the transmission and responds in a stepless manner, that is independently of the division of any locking members.
Particularly advantageously, and in accordance with a further advantageous aspect of the present disclosure, regions which can be directly deformed can be provided at the auxiliary worm gear.